With the Ninth Circuit's opinion in al-Kidd v. Ashcroft holding that material witness detentions may not be used as a pretext to hold suspects, it is worth noting that as a practical matter the power has never been used any other way. The practice dates make to the 1840s as professional police departments were being created. In the mid-nineteenth century policing was becoming a career. For the first time, there were incentives to investigate crime; law enforcement provided opportunities for long-term retention and promotion. Officers employed by newly-established police departments began to aggressively investigate crime using powers unimaginable to their constable and night-watch predecessors. Among these new powers was the ability to detain material witnesses. Officers began to detain suspects, whom they lacked adequate suspicion to charge, as witnesses. As the public became aware of the incarceration of those identified only as "witnesses," officer found the public very unwilling to cooperate in investigations for fear of being held for the crime of possessing helpful information. In New York, the Police Department asked the legislature in the late nineteenth century to allow only the detention of witnesses suspected of being accomplices. The legislature's acquiescence to the law enforcement request demonstrates not only the rising influence of law enforcement interests in the late-nineteenth century, it also demonstrates that the public was comfortable with material witness detentions only when they were used as a pretext to hold suspects.